This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Some conventional conveyor belts which are used in heavy duty applications are typically comprised of a cured rubber or polyvinyl chloride (PVC) based material as a top layer, a cured rubber or PVC based material as a bottom layer, and a reinforcement layer (a carcass) having a warp and weft, disposed between the top layer and the bottom layer. The cured rubber or polyvinyl chloride based material may also serve to adhere various components of the reinforcement layer. For example, individual layers and reinforcing elements included in the carcass may be encapsulated in a matrix of polymeric elastomeric resin. The individual layers are saturated with the liquid elastomer-forming polymeric resin prior to being joined together, and the reinforcing elements may be inserted, for example, by tufting, sewing, or stitch-bonding. In cases where the liquid saturate is a polyvinylchloride plastisol, the resin is gelled, or otherwise cured, by application of heat. In cases where cured rubber is used, the reinforcing elements may be entrained in a bonding rubber layer, and cured along with the top layer and the bottom layer.
Oxidized polyethylenes are known and are taught by U.S. Pat. Nos. 2,683,141 and 3,060,163 to Erchak. They are used to form stable, translucent emulsions for use in floor waxes, in coatings for asbestos shingles, paper and textiles, and in inks for application to various surfaces. They have been incorporated into thermoplastic polypropylene compositions containing EPDM compositions, such as those described in U.S. Pat. No. 4,990,568 to Benefield et al. In Benefield a thermoplastic polypropylene is modified with EPM or EPDM and an oxidized or carboxylated polyolefin, in at an amount of 2 to 20% of the elastomer, to improve the problem of adherence of coatings applied to the surfaces of articles formed from the thermoplastic elastomers.
The use of mechanical cleaning systems for conveyor belts is known. For example, there are belt scrapers which are applied especially in the region of the direction-changing rollers. The disadvantage of such belt scrapers is that premature wear of the belt cover is caused during the scraping operation by the direct contact of the scraper and the rubber cover. Because severe heavy duty belt scrapers have been shown to be unsatisfactory, it has been suggested to provide conveyor belts with dirt-repelling cover layers.
Some conveyor belts use a coating of plastic or polymer to prevent the build-up and dirtying of conveyor belts during the transport of the most different goods, especially mass goods. Some of these conveyor belts have a load carrying surface with coating or film of polyethylene, to provide anti-adhesive effect. However, an inadequate ability to bend the belt conveyor coated with polyethylene has been shown. Additionally, coatings or films applied to the outer surface of cover layers for rubber articles, such as hoses, conveyor belts, power transmission belts, and the like, are prone to delamination or erosion from the cover surface during the usable service like of the article, thereby losing the resistance to baking-on, dirtying or otherwise accumulation of material on the cover.
Thus, there is an ongoing need for rubber articles, such as conveyor belts, formed of materials which provide high durability, improved anti-stick and/or easy-release properties for their covers, while not being detrimental to other useful belt properties (i.e. abrasion resistance, troughability level, etc), such need met, at least in part, with embodiments according to the following disclosure.